The present invention relates to the field of image processing. More specifically, in one embodiment the invention provides a method and apparatus for determining the skew of a document containing text and/or graphics and, optionally, adjusting the skew of the document to a desired angle.
In many image processing applications it is desirable to determine skew of a document image. For example, for a text image skew is the angle at which lines of the text image differ from a pre-selected reference line, such as a horizontal line. Optical character recognition systems are exemplary of an image processing system in which it would be desirable to know the angle of skew of text since such systems typically scan horizontally through a portion of a document when processing an image of the document. If a text image is not properly oriented, OCR systems may have difficulty in "recognizing" individual characters and, in severe cases, may actually scan through multiple lines of text.
A variety of methods and devices for determining document skew have been proposed. While meeting with some success, prior methods have met with a variety of limitations. For example, some methods/devices require non-conventional or special purpose hardware, increasing the complexity and cost of such systems. Some systems require unacceptable amounts of computer processing time or computer processing capability. Still other methods operate only on text or require that specialized data representations be utilized.
From the above it is seen that an improved method and apparatus for determining and adjusting document skew is desired.